Early development of vertebral column and appendicular skeleton in Naozhou Larimichthys crocea (Richardson, 1846).

Understanding the developmental sequence characteristics of the vertebral and appendicular skeletons of the larvae and juveniles of Larimichthys crocea (Naozhou population) can provide theoretical basis for seedling cultivation, environmental adaptation, and taxonomic identification. The cartilage-bone double staining method was used to stain, observe, and analyse the vertebrae, pectoral fins, anal fins, caudal fins, and dorsal fins of the larvae and juveniles of L. crocea (0-30 days post-hatching [DPH]). Results showed that the notochord of the larvae and juveniles of L. crocea was tubular. At 6 DPH, there was obvious segmentation. At 8 DPH, the neural arches began to differentiate, and at 10 DPH, the haemal arches began to differentiate, with complete segmentation of the notochord. At 14 DPH, the dorsal and ventral ribs became clear, and the neural and haemal spines were completely formed by the elongation of the neural and haemal arches, respectively. At 18 DPH, the vertebral bones began to ossify, and ossification was complete at 28 DPH. The median fins of the larvae and juveniles of L. crocea formed in the order of caudal fin, anal fin, and dorsal fin. Among the 800 L. crocea larvae samples, 248 were observed to have skeletal deformities, with a deformity rate of 31.00%. The spine of L. crocea consists of 26 vertebrae, with developmental abnormalities mainly including vertebral anterior convexity, bifurcation of neural spines, vertebral body fusion, and redundancy of neural spines. The above results provide a theoretical basis for enriching the developmental biology of L. crocea.